1. Field of the Invention
The present invention relates to a fuel injector for an internal combustion engine.
2. Description of the Related Art
According to Japanese Unexamined Patent Publication No. 5-272432, the injection hole of a fuel injector is formed like a slit. The fuel injected from this injection hole forms a flat triangular spray having a relatively small thickness and in which nearly all the fuel comes into sufficient contact with the air and is favorably atomized. The injection hole is communicated with a single fuel reservoir in the fuel injector. The fuel is injected through the injection hole as the pressure of the fuel in the fuel reservoir is increased.
In the above-mentioned fuel injector, the velocity of injection of the fuel from each portion of the injection hole is not uniform even if the same fuel pressure is exerted from the fuel reservoir on each of the portion of the injection hole, i.e., the velocity of injection at both ends is affected by the wall surfaces of the injection hole and is generally retarded behind that of the central portion of the injection hole. When the velocity of injection is set to favorably diffuse the fuel that is injected from the central portion of the injection hole, therefore, the velocity of injection of the fuel from each end of the injection hole is very low, and the fuel is excessively diffused on both sides of the triangular fuel spray. Therefore, the above-mentioned fuel injector is not capable of producing a fuel spray which provides a generally favorable degree of diffusion.